JP2000244847A - Projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correct an out-of-focus state that is caused by the change of the refractive index or the ambient temperature due to the temperature change of a liquid coolant and to always obtain the best projection images. SOLUTION: An automatic adjustment mechanism 7 can perform focus adjustment of a focus adjustment lens 3a via the drive of a motor (7a) or the like, and is mounted on the lens 3a. A temperature sensor 8 is contained in a coupling 5 constructing a projector 3A to detect the temperature of the liquid coolant enclosed in the coupling 5 and to give the temperature detection result 8a to a motor control part 9. The part 9 produces a drive control signal 9a from the result 8a to correct an out-of-focus state that is caused by the temperature change of the coolant. Then the part 9 controls the revolving direction and rotational frequency of the motor (7a) of the mechanism 7 on the basis of the signal 9a. Thus, it's possible to always perform automatic correction of the out-of-focus state and accordingly to always obtain the best projection images despite the temperature change of the coolant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT projection type display device using a CRT, such as a projection television (hereinafter, referred to as a PJTV), and more particularly to a drift caused by a rise in temperature of a cooling liquid loaded in a coupling. The present invention relates to a projection display device capable of automatically correcting a generated lens focus shift and obtaining a good projection image.

[0002]

2. Description of the Related Art Heretofore, a CRT projection type display device using a CRT (also called a projection tube) has been widely used. C
Although the use of RT is effective in terms of high image quality, further higher quality and higher brightness are desired in response to strong demands of users.

[0003] In general, a CRT projection type display device comprises, for example, a rear projection type display device having a built-in CRT, or a system composed of a CRT and a screen without a built-in CRT. There is a front projection type display device for enlarging and projecting.

In the case of the former built-in type display device, image light of each color is generally obtained by, for example, a CRT provided for each of the three primary colors of R, G, and B, and these image lights are converted into an optical device such as a projection lens. An image based on an input video signal as a video source is enlarged and displayed on a predetermined area of the screen by projecting through the system and irradiating the screen via a reflecting means provided on the back surface of the main body. On the other hand, the latter front projection display device enlarges and projects the image light obtained by each CRT to a screen provided in the front direction through an optical system such as a projection lens, and thereby the same is applied to the screen. The image based on the input video signal is enlarged and displayed.

FIG. 3 shows an example of such a rear projection type display device.

FIG. 3 shows a configuration example of a rear projection type display device, and is a schematic configuration diagram for explaining an optical system used in the device.

As shown in FIG. 3, the rear projection type display device comprises:
A projector 3 housed in a main body (housing) and configured by a projection tube 4, a focus adjustment lens 3a, and the like; a reflecting mirror 2 for reflecting image light projected from the projector 3;
It is composed of a screen 1 and the like for projecting the projection image light from the reflection mirror 2.

In the above configuration, generally, for example,
Image light of each color is obtained by a CRT provided for each of the three primary colors G and B, and these image lights are focused on a focus adjusting lens 3a.
By projecting the light through a projection lens and irradiating the screen 1 with a reflection mirror 2 provided on the rear surface of the main body, an image is enlarged and displayed on a predetermined area of the screen 1. By forming the optical path provided with the reflection mirror 2 in this manner, there is an advantage that the depth of the main body of the display device can be reduced.

Incidentally, in such a projection type display device, an optical system member provided in each CRT is improved in order to ensure the display performance.

FIGS. 4 and 5 are views for explaining the opto-coupling of the projector which has been improved to ensure the display performance as described above, and FIG. 4 is a perspective view showing a schematic configuration of the projector. FIG. 5 is a perspective view of the system as viewed from the rear side.

As shown in FIG. 4, in a projector 3 used in a general projection type display device, a normal projection tube 4 is connected to a focus adjustment lens 3a by an optical coupling. The focus adjustment lens 3a is provided with a lens focus adjustment lever 6 for adjusting the lens focus on its outer peripheral portion. When a focus shift occurs, the lens focus adjustment lever 6 is moved to the slide groove 6a. By changing the distance between the lens 3a and the projection tube 4 by appropriately adjusting the distance along the axis, a focal length suitable for the optical system path can be obtained, and the optical focus can be adjusted. At this time, by screwing and fixing a set screw provided on the focus adjustment lever 6, the focus state can be maintained.

The mounting state of the projection tube 4 and the coupling 5 is such that the fluorescent screen of the projection tube 4 is mounted in the coupling 5 as shown in FIG.

In the case of enlarged projection, as described above, the image displayed on the fluorescent screen of the projection tube 4 is enlarged and projected as image light on the screen 1 (see FIG. 3) via the focus adjustment lens 3a.

In the opto-coupling system, a cooling liquid having substantially the same refractive index as that of the glass is sealed in the coupling block 5 (see FIG. 4). Suppresses the reflection of light that has occurred at the boundary surface due to the difference with the refractive index with air,
The brightness and contrast are improved.
Further, it is conceivable that the panel temperature rises due to the phosphor screen power of the projection tube 4 for increasing the brightness, and the brightness rise and panel cracks may occur due to this temperature rise. Thus, by cooling the periphery of the coupling 5 including the panel of the projection tube 4, these inconveniences are prevented.

However, in the projection type display device provided with such a cooling means, the cooling liquid in the coupling 5 is used to cool the fluorescent screen of the projection tube 4 or its peripheral portion. When used, the temperature of the cooling liquid itself may increase. In such a case, since the cooling liquid has a characteristic that the refractive index changes with temperature, the refractive index decreases as the temperature increases. In other words, when the refractive index of the cooling liquid is reduced, the focus of the lens is connected in front of the screen, and a focus shift occurs, so that the best projected image cannot be obtained.

If the focus is adjusted when the temperature of the coolant rises and becomes stable, the power of the device is turned off. When the power of the device is turned on again when the temperature of the coolant drops, the above-mentioned temperature is reduced. A focus shift opposite to that at the time of ascending occurs. That is, since the refractive index of the cooling liquid is relatively high, the lens is focused outside the screen, and also in this case, the best projected image cannot be obtained.

Further, since the focus adjusting lens 3a is easily affected by the ambient temperature, it cannot always maintain stable focus performance in various environments, that is, always obtains the best projected image. Was difficult.

[0018]

As described above, the conventional projection display device employs the opto-coupling in order to secure the surface performance of the display device or to increase the brightness.
In this opto-coupling, the refractive index changes due to a change in the temperature of the cooling liquid used, causing a lens focus shift. Even if this is corrected using a lens adjustment lever, the change in the temperature is caused by the temperature change. There is a problem that the focus shift cannot be corrected and the best projected image cannot always be obtained. In addition, since a focus adjustment lens that is easily affected by the ambient temperature is used, there is a problem that the best projected image cannot always be obtained in any environment.

In view of the above, the present invention has been made in view of the above problems, and has a configuration in which a focus shift caused by a change in refractive index due to a change in temperature of a coolant or a change in ambient temperature is automatically corrected. It is an object of the present invention to provide a projection display device that can always obtain the best projection image.

[0020]

A projection display apparatus according to the present invention uses a CRT to project image light based on a video signal onto a screen through a focus adjusting lens capable of adjusting a focus, and to project the image light on the screen. In a projection display device in which a focus adjustment lens is coupled via an opt coupling, a temperature detecting means for detecting a temperature of a cooling liquid provided in the opt coupling, and mounted on the focus adjustment lens and driven by a motor An automatic adjustment mechanism configured to adjust the distance between the focus adjustment lens and the CRT, and the motor is controlled based on a detection result of the temperature detection means to automatically adjust a focus shift caused by a temperature change of the coolant. And a control means for performing correction.

According to the present invention, the provision of the temperature detecting means, the automatic adjusting mechanism, and the control means makes it possible to automatically correct a focus shift caused by a change in the temperature of the coolant.

[0022]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of a projection display apparatus according to the present invention, and is a configuration diagram for explaining a configuration of a main part of a projector mounted on the apparatus.

In the apparatus shown in FIG. 1, the same components as those in the projector shown in FIG. 4 or 5 are denoted by the same reference numerals.

In this embodiment, an automatic adjustment mechanism 7 for mechanically adjusting the focus adjusting lens 3a in the projector 3A mounted on the projection display device.
And a temperature detecting means 8 provided in the opto-coupling.
Control means 9 for controlling the automatic adjustment mechanism 7 so as to always provide an optimum focus in accordance with the detection result from the apparatus, thereby causing a change in the refractive index due to a change in the temperature of the coolant or a change in the ambient temperature. The focus shift is automatically corrected.

The overall configuration of the projection type display apparatus according to the present embodiment includes a projector 3A including a projection tube 4 housed in a main body (housing), a focus adjustment lens 3a, and the like, and a projected image from the projector 3A. It is composed of a reflection mirror 2 for reflecting light, a screen 1 for projecting image light projected from the reflection mirror 2, and the like, and is the same as FIG.

In the above configuration, generally, for example,
Image light of each color is obtained by a CRT provided for each of the three primary colors G and B, and these image lights are focused on a focus adjusting lens 3a.
And the like, and irradiates the screen 1 via a reflection mirror 2 provided on the rear surface of the main body, so that an image based on an input video signal as a video source is enlarged and displayed on a predetermined area of the screen. You.

The projector 3A of the projection type display device of the present embodiment employs the same opto-coupling as in the prior art as described with reference to FIGS. A cooling liquid having substantially the same refractive index as glass is sealed therein.

By the way, in the above opto coupling,
Since the refractive index changes due to a change in the temperature of the cooling liquid, there is a disadvantage that a lens focus shift occurs.

Therefore, in the present embodiment, as shown in FIG. 1, an automatic adjustment mechanism 7 for driving the lens adjustment lever 6 mechanically by a driving unit such as a motor to adjust the focus to the focus adjustment lens 3a. Is provided. Although not shown, a temperature sensor 8 is mounted in the coupling 5 as temperature detecting means for detecting the temperature of the coolant in the coupling 5.

The temperature sensor 8 is connected to the coupling 5
The temperature of the cooling liquid inside is detected, and the temperature detection result 8 a is given to the motor control unit 9.

The motor control section 9 generates a drive control signal 9a for obtaining an optimum focus based on the temperature detection result 8a from the temperature sensor 8, and the drive control signal 9a
The drive by the automatic adjustment mechanism 7 is controlled using a.
The motor control unit 9 may be included in a control unit that controls the entire projection display device, or may be provided as a separate member.

FIG. 2 is a configuration diagram showing a specific configuration example of the above-mentioned automatic adjustment mechanism, in which only main parts are shown.

The structure of the automatic adjustment mechanism 7 will be described with reference to FIG. 2. The focus adjustment lens 3a is provided with a lens focus adjustment lever 6 for adjusting the focus of the lens.

A screw hole is provided in the vicinity of the grip portion of the lens focus adjustment lever 6, and the focus adjustment screw 7b screwed into the screw hole is rotated about the focus adjustment screw 7b as a rotation axis. Motor 7a for transmitting force
Is installed. That is, the focus adjustment screw 7b
And the shaft of the motor 7a are connected and fixed so that they can be mounted on a shaft. The connection between these members may be configured to be connected and fixed via a transmission mechanism or the like.

The motor 7a includes the focus adjusting lens 3
a, or the coupling 5 is fixed via a fixing member or the like. Therefore, during rotation driving, vibration or the like does not occur, and the rotational force is reliably applied to the focus adjusting screw 7b.
And the slide operation of the focus adjustment lever 6 can be smoothly performed.

Therefore, according to the above configuration, the temperature of the coolant inside the coupling 5 is always detected by the temperature sensor 8 in the coupling 5, and the temperature detection result 8 a is given to the motor control unit 9, whereby the motor control unit 9 generates a drive control signal 9a for achieving an optimum focus from the supplied temperature detection result 8a, and generates the drive control signal 9a.
It is possible to control the rotation direction and the rotation amount of the motor 7a having the above configuration based on the above. That is, since the rotation direction and the rotation amount of the motor 7a are controlled, the left and right sliding directions and the sliding amount of the lens focus adjustment lever 7 are also controlled in conjunction with the focus adjustment screw 7b and the screw hole. The focus adjustment by the lens focus adjustment lever 6 can be optimally performed.

The control of the number of rotations of the motor 7a by the motor control unit 9 is not limited to the temperature detection result 8a,
For example, the control is performed based on the degree of the change in the temperature of the coolant and the change in the focus, and the ratio of the speed change mechanism when the speed change mechanism is provided. The information indicating the degree of the change in the temperature of the coolant and the change in the focus in this case is:
For example, it may be configured to store in advance in a storage unit such as a memory provided in the control unit, read out the data as appropriate, and determine the drive control signal 9a necessary for performing the optimum focus adjustment, or the focus control signal 9a. A detecting means for detecting the focus value of the lens 3a may be provided, and the drive control signal 9a necessary for the optimum focus adjustment may be determined using the focus value from the detecting means as described above.

Next, the focus correction control operation by the motor control unit will be described in detail.

Now, it is assumed that the panel temperature of the projection tube 4 in the projector 3A shown in FIG. 1 has risen.

Then, the temperature of the coolant in the coupling 5 rises. For this reason, the refractive index of the cooling liquid is reduced, and the focus of the lens is connected in front of the screen 1 (see FIG. 3) due to the decrease in the refractive index, and a focus shift occurs.

At this time, the temperature sensor 8 detects this temperature rise and gives it to the motor control section 9 as a temperature detection result 8a.

Then, when the temperature of the coolant rises, the motor control unit 9 generates a drive control signal 9a from the supplied temperature detection result 8a and the like so as to obtain an optimum focus, and
The motor 7 of the automatic adjusting mechanism 7 is controlled based on the drive control signal 9a.
The direction of rotation and the amount of rotation (number of rotations) are controlled. By sliding the lens focus adjustment lever 6 with the driving of the automatic adjustment mechanism 7, the focus adjustment lens 3a approaches the direction of the projection tube 4, and as a result, the image forming distance is extended, and The focus will match. In other words, the projected image on the screen 1 becomes a good focus-corrected image.

Conversely, it is assumed that the power supply of the projection type display device is turned off and the temperature of the coolant itself drops. At this time, if the best focus adjustment is performed when the temperature rises, the refractive index changes again due to the decrease in the temperature of the cooling itself.
(See FIG. 3), and the focus shift will occur again.

At this time, the temperature sensor 8 detects this temperature drop and gives it to the motor control section 9 as a temperature detection result 8a.

Then, when the temperature of the coolant decreases, the motor control section 9 generates a drive control signal 9a based on the supplied temperature detection result 8a and the like so as to obtain an optimum focus.
The motor 7 of the automatic adjusting mechanism 7 is controlled based on the drive control signal 9a.
The direction of rotation and the amount of rotation (number of rotations) are controlled. By sliding the lens focus adjustment lever 6 with the drive of the automatic adjustment mechanism 7, the focus adjustment lens 3a is moved away from the direction of the projection tube 4, and as a result, the image formation distance is shortened, and as a result, the screen 1 Will match the focus. That is, even in such a case, the projected image becomes a good focus-corrected image.

Therefore, according to the present embodiment, by providing the projector 3A of the projection type display device with the automatic adjustment mechanism 7, the temperature sensor 8 and the motor control unit 9, the temperature of the coolant used for the opto-coupling can be reduced. Even if the refractive index changes due to a change in the ambient temperature or a change in the ambient temperature, the focus can be automatically corrected so that the best focus is always obtained even when the focus shifts. Is possible, which greatly contributes to higher quality of the projected image.

In this embodiment, the rear projection type display device equipped with a CRT projection type projector has been described. However, the present invention is not limited to this, and may be applied to a projector in a front projection type display device. It is possible, and the same effects as in the above embodiment can be obtained.

[0048]

As described above, according to the present invention,
When a focus shift occurs due to a change in the refractive index or a change in the ambient temperature due to a change in the temperature of the coolant, it is possible to provide a projection display device that can automatically correct the focus shift and always obtain the best projected image. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of a projection display device of the present invention, and showing a schematic configuration of a projector equipped with the device.

FIG. 2 is a configuration diagram showing a specific example of an automatic adjustment mechanism provided in the projector of FIG.

FIG. 3 is a configuration diagram illustrating a configuration example of a rear projection display device.

FIG. 4 is a schematic configuration perspective view of an opto-coupling employed in a projector of a conventional projection display device.

FIG. 5 is a configuration perspective view of the projector of FIG. 4 as viewed from the rear side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Screen, 2 ... Reflection mirror, 3 ... Projector (CRT), 3a ... Focus adjustment lens, 4 ... Projection tube, 5 ... Coupling, 6 ... Lens focus adjustment lever, 6a ... Guide groove, 7 ... Automatic adjustment mechanism 7a: motor; 7b: screw for focus adjustment; 8: temperature sensor (temperature detecting means); 9: motor control unit.

Claims (3)

[Claims] An image light based on a video signal is enlarged and projected on a screen via a focus adjusting lens capable of adjusting a focus using a CRT, and the CRT and the focus adjusting lens are coupled via an optical coupling. In the projection display device, a temperature detection unit that detects a temperature of a cooling liquid provided in the opto-coupling, and is mounted on the focus adjustment lens, and a distance between the focus adjustment lens and the CRT can be adjusted by driving a motor. An automatic adjustment mechanism configured to: and a control unit that controls the motor based on a detection result of the temperature detection unit and automatically corrects a focus shift caused by a temperature change of the coolant. Projection display device. 2. The automatic adjustment mechanism includes: an adjustment lever provided on an outer periphery of the focus adjustment lens, which is capable of adjusting a focus; a focus adjustment screw screwed into a screw hole provided on the adjustment lever; 2. The projection type display device according to claim 1, wherein the projection type display device is constituted by a motor mounted around an adjustment screw as a rotation axis. 3. The control means determines a rotation direction and a rotation amount of a motor in the automatic adjustment mechanism from a temperature detection result by the temperature detection means, and performs drive control of the motor to automatically correct a focus shift. The projection type display device according to claim 1, wherein: